Pakistan's Prime Minister Imran Khan is no longer the Prime Minister of Pakistan.

The opposition's no-trust motion against Prime Minister Imran Khan succeeded an hour past midnight on Sunday, with 174 members in the 342-strong house voting in favour of the resolution.

PML-N's Ayaz Sadiq, who was chairing the session after Asad Qaiser resigned as speaker, announced the result, after which Imran Khan ceased to hold the office of prime minister, according to Article 95 of the Constitution.

Imran Khan is the first prime minister in Pakistan's history to have been removed from office through a no-confidence vote. Before him, Shaukat Aziz in 2006, and Benazir Bhutto in 1989, survived the moves against them.

PML-N spokesperson Marriyum Aurangzeb said Sadiq could not cast his vote as he was chairing the session. PTI dissenting members did not cast their votes either.

Before adjourning the session, Sadiq said the nomination papers for the new prime minister may be submitted by 2pm today (Sunday) and scrutiny would be done by 3pm. He summoned the session on Monday at 11am and said the new premier would be elected then.

Later, it was that the assembly would meet at 2:00pm instead.

Earlier, after announcing the result, Sadiq gave the floor to Shehbaz Sharif, who is the joint opposition's candidate for the post of prime minister. Shehbaz paid tribute to all leaders part of the joint opposition, and vowed that the "new regime would not indulge in politics of revenge".

"I don't want to go back to bitterness of the past. We want to forget them and move forward. We will not take revenge or do injustice; we will not send people to jail for no reason, law and justice will take its course," Shehbaz said.

After Shehbaz, Bilawal took the floor and congratulated the house for passing a no-trust resolution against a premier for the first time in history.

"On April 10,1973, this house approved the Constitution. On April 10, 1986, Benazir Bhutto ended her exile and returned to Lahore for her struggle against Gen Ziaul Haq," Bilawal recalled.

"Today is April 10, 2022, and the one we had declared selected, the non-democratic burden this country was bearing for the past 3 years, today, April 10, 2022, welcome back to purana (old) Pakistan."

"I have been a member of this house for 3-4 years and I have learned a lot in these years. My message to youth is that they should never give up on their dreams, nothing is impossible ... democracy is the best revenge," Bilawal said.

Minutes before voting began, National Assembly Speaker Asad Qaiser resigned from his post, saying he could not take part in a foreign conspiracy to oust the prime minister.

Qaiser's resignation came almost 15 minutes before midnight, which according to legal experts, was the deadline to implement the Supreme Court's orders to conduct voting on the no-trust motion. By that time, activity was seen at the apex court's premises. A Dawn correspondent, who was present at the building's gate, said official cars were seen entering and exiting.

Some media reports suggested that the larger bench which had issued the April 7 order had fixed the matter for hearing at 12:05am.

Before announcing his resignation, Qaiser said that he had received "important documents" from the cabinet, which he invited the leader of the opposition and the chief justice of Pakistan to see.

"In line with our laws and the need to stand for our country, I have decided that I can't remain on the position of speaker and thereby resign," he said.

"Because this is a national duty and it is the Supreme Court's decision, I will ask the panel chairman Ayaz Sadiq to run the session," Qaiser said.

After Sadiq took the chair, he paid tribute to Qaiser for remaining with his party and opting for an "honourable exit".

"He [Qaiser] had a very good relationship with all of us, a working relationship. He tried to conduct all these proceedings with dignity and together with the opposition."

Then, Sadiq asked for bells to be rung in the house for five minutes to notify members that the voting process was about to begin, after which the doors of the assembly were closed.

Voting on the resolution then began at 11:58pm, and members in favour of the resolution were asked to exit the gate on Sadiq's left. Sadiq then adjourned the session for four minutes since according to rules, a sitting of the same session cannot continue past midnight.

The session then resumed at 12:02am, with recitation of the Holy Quran and naat. Following that, the voting process continued, with lawmakers confirming their votes by writing their names in a register placed near one of the assembly doors.

Bells were then rung for another two minutes to signal that voting had ended and members returned to their seats.

All government members but Ali Muhammad Khan had walked out of the house and boycotted the session after Qaiser announced his resignation as speaker.

As the lone voice in the house supporting Imran Khan, Ali delivered a fiery speech, reminding the former opposition of his leader's achievements, claiming that Imran Khan "sacrificed his government but did not accept slavery".

"God willing, Imran Khan will be back ... he will be back with a two-thirds majority," Ali said.

"Bilawal, years ago your grandfather gathered the Muslim ummah in Islamabad. He did it once, but my leader gathered [the ummah] twice in two months.